Can HCV affect the efficacy of anti-HIV treatment?

1,3-Diazepine: A privileged scaffold in medicinal chemistry

Privileged structures have been widely used as effective templates for drug discovery. While benzo-1,4-diazepine constitutes the first historical example of such a structure, the 1,3 analogue is just as rich in terms of applications in medicinal chemistry. The 1,3-diazepine moiety is present in numerous biological active compounds including natural products, and is used to design compounds displaying a large range of biological activities. It is present in the clinically used anticancer compound pentostatin, in several recent FDA approved β-lactamase inhibitors (e.g., avibactam) and also in coformycin, a natural product known as a ring-expanded purine analogue displaying antiviral and anticancer activities. Several other 1,3-diazepine containing compounds have entered into clinical trials. This heterocyclic structure has been and is still widely used in medicinal chemistry to design enzyme inhibitors, GPCR ligands, and so forth. This review endeavours to highlight the main use of the 1,3-diazepine scaffold and its derivatives, and their applications in medicinal chemistry, drug design, and therapy. We will focus more particularly on the development of enzyme inhibitors incorporating this scaffold, with a strong emphasis on the molecular interactions involved in the inhibition mechanism.

Systematic review and meta-analysis of hepatitis C virus infection and HIV viral load: new insights into epidemiologic synergy

INTRODUCTION

Hepatitis C virus (HCV) and HIV infection frequently co-occur due to shared transmission routes. Co-infection is associated with higher HCV viral load (VL), but less is known about the effect of HCV infection on HIV VL and risk of onward transmission.

METHODS

We undertook a systematic review comparing 1) HIV VL among ART-naïve, HCV co-infected individuals versus HIV mono-infected individuals and 2) HIV VL among treated versus untreated HCV co-infected individuals. We performed a random-effects meta-analysis and quantified heterogeneity using the I(2) statistic. We followed Cochrane Collaboration guidelines in conducting our review and PRISMA guidelines in reporting results.

RESULTS AND DISCUSSION

We screened 3925 articles and identified 17 relevant publications. A meta-analysis found no evidence of increased HIV VL associated with HCV co-infection or between HIV VL and HCV treatment with pegylated interferon-alpha-2a/b and ribavirin.

CONCLUSIONS

This finding is in contrast to the substantial increases in HIV VL observed with several other systemic infections. It presents opportunities to elucidate the biological pathways that underpin epidemiological synergy in HIV co-infections and may enable prediction of which co-infections are most important to epidemic control.

Dual inhibition of HCV and HIV by ring-expanded nucleosides containing the 5:7-fused imidazo[4,5-e][1,3]diazepine ring system. In vitro results and implications

Examples of ring-expanded nucleosides (RENs), represented by general structures 1 and 2, exhibited dual anti-HCV and anti-HIV activities in both cell culture systems and the respective target enzyme assays, including HCV NTPase/helicase and human RNA helicase DDX3. Since HCV is a leading co-infection in late stage HIV AIDS patients, often leading to liver cirrhosis and death, the observed dual inhibition of HCV and HIV by the target nucleoside analogues has potentially beneficial implications in treating HIV patients infected with HCV.

Effect of hepatitis C virus on immunological and virological responses in HIV-infected patients initiating highly active antiretroviral therapy: a meta-analysis

Co-infection of human immunodeficiency virus (HIV) with hepatitis C virus (HCV) is rather common. In the era of highly active antiretroviral therapy (HAART), viral hepatitis could result in adverse outcomes in HIV+ patients. The current meta-analysis aims to evaluate the impact of HCV on immunological and virological responses after HAART initiation in HIV/HCV co-infected individuals by synthesizing the existing scientific evidence. A comprehensive search of electronic databases was performed. Eligible studies were analysed using univariate and multivariate meta-analytic methods. Totally, 21 studies involving 22533 individuals were eligible. The estimated summary difference in CD4 cell counts increase between HIV and HIV/HCV co-infected subjects after 3-12 months on HAART was 34.86 cells/mm(3) [95% confidence interval (CI): 16.82-52.89]. The difference was more prominent in patients with baseline CD4 counts below 350 cells/mm(3) (38.97, 95% CI: 20.00-57.93) and attenuated 2 years later (13.43, 95% CI: 0.83-26.04). The analysis of ratio measures yielded similar findings. The virological control remained unaffected by the presence of HCV (adjusted Hazard Ratio for co-infected patients vs those with HIV alone: 0.99, 95% CI: 0.91-1.07). The bivariate meta-analytic method confirmed the results of the univariate approaches. This meta-analysis supports the adverse effect of HCV on immune recovery of HIV+ patients initiating HAART, especially of those with initially impaired immunologic status. Although this effect diminishes over time, early administration of HAART in the setting of co-infection seems to be justified.

Changes in hepatitis C virus (HCV) viral load and interferon-alpha levels in HIV/HCV-coinfected patients treated with highly active antiretroviral therapy

BACKGROUND

Reports are mixed as to whether highly active antiretroviral therapy (HAART) increases liver transaminase levels or hepatitis C virus (HCV) titers in HIV/HCV-coinfected individuals. It is hypothesized that increases in HCV RNA titers may result from changes in endogenous interferon-alpha (IFN-alpha) production.

METHODS

HIV/HCV-coinfected patients receiving HAART were tested at baseline, 1, 2, 3, 6, and 9 months for liver transaminase levels, HIV and HCV viral loads, and IFN-alpha. Linear regression analysis was used to determine the effect of HAART on liver transaminase levels, HCV viral load, and IFN-alpha.

RESULTS

Initiating HAART did not increase liver transaminase levels in majority of cases. In patients (n = 30) with baseline HIV titer >10,000 copies/mL, HCV titers increased 0.69 log10 and IFN-alpha decreased -0.96 log10 during HAART, in association with a > or =0.5 log10 decrease in HIV titer. As HIV titers reached their nadir approximately 4 months after initiation of HAART, HCV titers remained 0.54 log10 and IFN-alpha -0.71 log10 above and below baseline levels, respectively. HCV titers and IFN-alpha levels did not change from baseline in patients with baseline HIV titer < or =10,000 copies/mL.

CONCLUSIONS

Coinfected patients did not have evidence of hepatoxicity HAART. In patients with baseline HIV titer >10,000 copies/mL, suppression of HIV replication by HAART was associated with an increase in HCV titer and a decrease in endogenous IFN-alpha levels.

Detection of HCV-RNA in saliva of HIV-HCV coinfected patients

The presence of HCV-RNA in saliva of patients with chronic hepatitis C provides a biological basis for the potential transmission of this virus. HCV viremia is particularly high in HCV-HIV-coinfected patients, which could favor the presence of HCV in their saliva. This study was designed to evaluate the prevalence of HCV in saliva of HCV-HIV-coinfected patients. Stimulated whole saliva was collected from 75 HCV-HIV-coinfected patients and 75 HCV controls. The presence of HCV-RNA in saliva was tested by a highly sensitive noncommercialized nested PCR, and analyzed in relation to demographic, clinical, and analytical variables. HCVRNA was detected in the saliva of 49 (65%) HCV-HIV-coinfected patients and 39 (52%) HCV controls. The presence of HCV in saliva was not related to any of the analyzed variables in HCV-HIV-coinfected patients. In the HCV control group a statistically significant relationship was demonstrated only between the detection of HCV-RNA in saliva and the viral load in peripheral blood (p < 0.001). Our results indicate that there is a trend toward a higher HCV-RNA prevalence in the saliva of HCV-HIV-coinfected patients.

[Rate and risk factors of liver toxicity in patients receiving antiretroviral therapy]

BACKGROUND

The benefit of highly active antiretroviral therapy (HAART) may be limited by the development of liver toxicity. The prevalence and risk factors of this complication using different antiretroviral drug combinations are not well known.

PATIENTS AND METHOD

Clinical charts of HIV-infected patients, previously naive for antiretroviral drugs, starting HAART between January 1997 and January 2000 were reviewed. Liver toxicity was scored according to increases in liver enzymes.

RESULTS

HIV infection had been acquired by intravenous drug use in 36 (40%) of 91 subjects recruited in the study. The rest had been infected through homosexual (38%) or heterosexual contact (22%). Overall, 43 patients (47%) were coinfected with hepatitis C (42%) and/or B (8%) viruses. Antiretroviral therapy included protease inhibitors (PI) plus two nucleosides in 48 individuals and non-nucleosides in 50. Baseline characteristics were similar across the different treatment groups. Liver toxicity was recorded in 30 (31%) subjects, and it was severe in 10 (11%). Cytolysis was the predominant pattern (28), while only one case of cholestasis and one with a mixed pattern were recorded. Coinfection with hepatitis B and/or C viruses was associated with liver toxicity (RR: 10.36; 95% CI, 1.38-77.56; p = 0.03) as was a high alcohol intake (RR: 3.35; 95% CI, 2.43-4.62; p = 0.01). No differences in the rate of hepatotoxicity were found when comparing PI and non-nucleoside containing regimens. The development of isolated hyperbilirubinemia (27%) was strongly associated with the use of indinavir (RR: 3.61; 95% CI, 1.81-7.21; p < 0.001).

CONCLUSIONS

Liver toxicity occurs in about one third of HIV-infected patients after initiating HAART, regardless of the drugs used, yet it is commonly mild and transient. A high alcohol intake and a coinfection with HCV/HBV constitute the most important predictive factors.

Treatment of hepatitis C virus and HIV co-infections

Hepatitis C coinfection is common in patients with HIV, particularly in injection-drug users. Hepatitis C virus levels tend to be higher in coinfected patients, and histologic progression is more rapid than in patients with HCV alone. The efficacy of interferon monotherapy in HIV patients with an adequate CD4 cell count is comparable to that observed in patients without HIV. The combination of interferon plus ribavirin and pegylated interferon will further improve response rates. Interferon therapy is associated with leukopenia and a decrease in absolute CD4 cell count. Some concern remains that ribavirin might reduce the activity of pyrimidine analogues such as zidovudine and stavudine, and HIV-RNA levels should be followed when these medications are given concurrently. It is hoped that in time, new drug development will make the multiple-drug therapeutic strategy that has been highly successful in the management of HIV feasible for the treatment of HCV.

Hepatitis B and hepatitis C co-infection in patients with HIV

HAART has increased the life expectancy of patients with HIV. However, as their life expectancy increases, it becomes increasingly important to focus on the management of concurrent illnesses such as chronic HBV and HCV infections which have the potential to increase mid to long term morbidity and mortality. Shared epidemiological risks have resulted in the HIV infected population having a higher incidence of both HBV and HCV than those uninfected with HIV. Co-infection with HIV modifies the natural history of HBV infection, increasing the rate of viral replication, risk of carriage and chronic hepatitis but without increasing liver necroinflammatory processes. In chronic HCV infection, the presence of HIV enhances the risk of severe liver disease. There is no evidence as yet that HBV directly impacts on HIV disease progression but HCV infection increases the risk of death or an AIDS defining illness and impairs CD4+ T cell recovery during antiretroviral therapy. Treatment of either hepatitis virus is complex because of pharmacokinetic interactions with components of HAART regimens.